The present invention generally relates to coating compositions and methods. More particularly, this invention relates to processes for recovering inorganic powder materials from a polymer-based coating composition used to deposit a polymer-based coating containing the inorganic powder material.
Various applications exist for polymeric coatings that contain an inorganic powder material, nonlimiting examples of which include paints and reflective coatings. Phosphor-containing and color conversion coatings for use in lighting applications are other examples under consideration. As known in the art, phosphors exhibit luminescence and are commonly used in fluorescent lamps, phosphor-based light-emitting diodes (LEDs), and various other light-generating units.
Silicone is a notable but nonlimiting example of a commonly used encapsulation material for LED-phosphor integration with LED epitaxial (epi) wafer and die fabrication, and is also commonly applied as a binder for remote phosphor-containing coatings on transparent and translucent substrates, for example, glass enclosures (domes) of LED devices. In the latter example, a phosphor powder is combined with the silicone binder to form a suspension that can be applied to a substrate, for example, using a spray coating or dip coating technique. While having various desirable characteristics, silicone has certain limitations, one of which is that silicone limits the ability to reclaim and recycle an inorganic phosphor powder that is contained in a portion of the suspension that does not adhere to the targeted substrate. In practice, this limitation may result in most of the phosphor powder being lost. This aspect of silicone is undesirable in view of the cost of phosphor materials, particularly if the phosphor powder is made up of rare earth-activated materials.